Rotary cutter heads for mineral mining machines

ABSTRACT

A rotary cutter head for mounting on a hollow drive shaft of a mineral mining machine comprises water powered, air flow inducing devices mounted remote from the axis of the rotary cutter head.

United States Patent Candy et al.

ROTARY CUTTER HEADS FOR MINERAL MINING MACHINES Inventors: John Albert Gandy, Bircoats near Doncaster; Albert Graham French. Willington, both of England Coal Industry (Patents) Limited, England Filed; Feb. 6, 1974 Appl. No.1 440,010

Assignee:

Foreign Application Priority Data Feb. 9, 1973 United Kingdom 06437/73 US. Cl. 299/8]; 299/12; 299/89;

175/213 Int. C13. EZIC 13/04; E21C 7/00; EZIB 21/0 0 Field of Search 299/81, 89, 12; 175/213 References Cited UNITED STATES PATENTS 8/1943 Burch et al. 175/213 X Sept. 9, 1975 3,422,913 1/1969 Young 175 213 3,603,644 9/1971 McCleery 299/12 3,747,982 7/1973 Agnew IaI.... 299/31 3,827,755 8/1974 Alien 299/81 FOREIGN PATENTS OR APPLICATIONS 1,301,182 7/1962 France 299/81 4/1968 United Kingdom 299/81 Primary ExaminerDavid H. Brown Attorney, Agent, or FirmStevens, Davis, Miller & Mosher [57] ABSTRACT A rotary cutter head for mounting on a hollow drive shaft of a mineral mining machine comprises water powered, air flow inducing devices mounted remote from the axis of the rotary cutter head.

15 Claims, 11 Drawing Figures SHEET l/I'IIIIA SHEET FIG}.

PATENTEU SEP 75 SHEET PATENTEUSEP 9W5 SHEET I I I I I 'I I I I I I I I FIGS.

PATENTEUSEP 9191's 3.904.246

sum e FlGb.

PATENTEUBEP 91915 #1804246 sum 8 FIG. 8.

PATENTED SEP 91975 SHEET FIG).

ROTARY CUTTER HEADS FOR MINERAL MINING MACHINES This invention relates to rotary cutter heads for mineral mining machines, the cutter heads being drivably mountable on rotary drive shafts of the machines and having cutter tools mounted around their outer peripheries for breaking mineral from working faces.

Frequently. when such a cutter head is used to break coal from a longwall coal face there is a tendency for methane emitted from the broken coal to concentrate around the cutter head which is operating in a buttock shielded from the main ventilation air flow. Such a concentration of methane can be dangerous, especially if the methane is allowed to collect in the vicinity of the cutting zone of cutter head until its concentration is within the explosive range i.e. S /r to I59? of methane. Once the concentration of methane is within this range it is possible for a spark generated by a cutter tool striking an intrusion in the coal face to ignite the methane which in turn could give rise to an explosion.

It is known for a mining machine to have a hollow drive shaft and for ventilator means comprising a water jet to be provided on the mining machine which induces a ventilating air flow along the hollow drive shaft of the rotary cutter head towards the cutting zone of the cutter head. Unfortunately. the use of such a ventilator means usually precludes the use of the hollow drive shaft for feeding dust suppression fluid to the cuttcr head. the fluid being distributed to nozzles provided on the cutter head adjacent to the cutter tools. Thus previously, it has been necessary to decide whether the hollow drive shaft should be used for conducting a ventilation air flow or whether it should be used for feeding dust suppression fluid to the cutter head. If the hollow drive shaft was used for ventilation then it was necessary to adopt a less efficient dust suppression system and install the nozzles for dust suppression fluid on the body of the mining machine remote from the cutter tools. Alternatively, if the hollow drive shaft was used for dust suppression purposes it was necessary to adopt a less efficient ventilating system and mount the ventilator means remote from the cutter head.

An object of the present invention is to provide an improved cutter head for a mineral mining machine.

According to the present invention a rotary cutter head for a mineral mining machine having a drive shaft extending towards the working mineral face, comprises a hub assembly drivably mountable on the drive shaft of the machine, a cylindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head. and ventilating means remote from the axis of rotation of the cutter head and including at least one air flow guide and an air flow inducing nozzle for directing fluid along the guide.

Preferably, the air flow guide extends through the hub assembly forming a passage which extends between the machine side and the working face side of the hub assembly.

The nozzle may be arranged for directing fluid along the guide so that an air flow is induced away from the working face side of the hub assembly and in which case a baffle may be provided on the machine side of the air flow guide.

Alternatively. the nozzle may be arranged for directing fluid along the guide so that an air flow is induced away from the machine side of the hub assembly.

The ventilator means may be arranged to induce an air flow through the cylindrical component and in which case the air flow guide means may be carried on loading vanes secured around the cylindrical component.

Advantageously, the rotary cutter head comprises a plurality of air flow guides. Conveniently a distributor is provided for feeding fluid fed along the machine's drive shaft to each of the nozzles.

Preferably, the cylindrical component provides a plurality of angularly spaced chambers and fluid is fed from the distributor to each of the chambers.

Advantageously fluid is fed from the chambers to dust suppression nozzles mounted on the cutter head.

The present invention also provides a rotary cutter head as defined above in combination with the mining machine.

By way ofexample only. six embodiments of the present invention will be described with reference to the ac companying drawings in which.

FIG. 1 shows a perspective view partly in section of a first embodiment of rotary cutter head mounted on a mining machine (only part of which is shown);

FIG. 2 is a diagrammatic sectional view taken along the axis of rotation of a rotary cutter head which is con structed as the cutter head of FIG. I except that it is of opposite hand to that of FIG. I, i.e. in use. the head rotates in the opposite direction.

FIG. 3 is a diagrammatic sectional view taken along the line lIIIlI of FIG. 2;

FIG. 4 is a diagrammatic sectional view taken along the axis of rotation of a rotary cutter head constructed in accordance with a second embodiment of the present invention and showing part of the head only;

FIG. 5 is a diagrammatic sectional view taken along the axis of rotation of a rotary cutter head constructed in accordance with a third embodiment of the present invention;

FIG. 6 is a diagrammatic sectional view taken along the line VIVI of FIG. 5;

FIG. 7 is an incomplete diagrammatic sectional view taken along the axis of rotation of a rotary cutter head constructed in accordance with a fourth embodiment of the present invention, the cutter head being of the same hand to the cutter head of FIG. 1;

FIG. 8 is an incomplete diagrammatic sectional view taken along the axis of rotation of a rotary cutter head constructed in accordance with a fifth embodiment of the present invention;

FIG. 9 is an incomplete diagrammatic end view of the rotary cutter head of FIG. 8 with an end plate removed; FIG. 10 is a perspective view of the end plate; and

FIG. 11 is an incomplete diagrammatic sectional view taken along the axis of rotation of a rotary cutter head constructed in accordance with a sixth embodiment of the present invention.

Referring firstly to FIGS. 1, 2 and 3 the first embodiment of rotary cutter head 1 is shown drivably mounted on a hollow drive shaft 2 of a coal mining machine 3 (only a part of which is shown) of the well known shearer type. In operation such a shearer machine traverses to and fro along a longwall coal face with cutter tools 4 mounted around the periphery of the cutter head winning coal from the working face. The broken coal is loaded by means of helical loading vanes 5 onto an armoured face conveyor [not shown) which extends along the face. As the cutter head 1 cuts the face it forms a buttock in the working face and thereby tends to be shielded from the main ventilation air flow along the face.

The cutter head 1 comprises a hub assembly 6 drivably mounted on the drive shaft 2 and retained in position by a spacer 7 and a key (not shown). A cylindrical component 8 is secured around the huh assembly and forms a mounting platform for the helical loading vanes 5 which in turn support cutter tool holders 9 for the cutter tools 4. The radially inner surface of the cylindrical component is provided with a plurality of elongated, angularly spaced plates 10 forming chambers 11, the ends of which are closed by end plates 12. The chambers 11 extend across substantially the whole of the cutter head and enable pipe connections 13 to be made to virtually any part of the cylindrical component from a plurality of nozzles 14 for dust suppression fluid provided adjacent to the cutter tool holders 4.

The rotary cutter head 1 also comprises ventilator means constituted by a plurality of air flow guides 15, each of which is formed by two plates 16 provided on the radially inner surface of the cylindrical component between two adjacent elongated plates 10 and extending from the machine side of the hub assembly to the working face side of the hub assembly. Although in the described embodiment the ventilator means comprises seven air flow guide means, the number could vary from one to more than seven depending upon the amount of induced ventilation required.

Air flow inducing nozzles 17 are provided for direct ing fluid along the air flow guide 15, respectively, each of the nozzles being mounted adjacent to the wall of the air flow guide and arranged to direct the fluid along the air flow guide so that an air flow is induced away from the working face and towards the machine.

A baffle 18 in the form of an annular perforated screen is provided on the cylindrical component 8 so as to extend across the outlets of the air flow guides.

The rotary cutter head 1 is provided with distribution means 20 for the dust suppression fluid. The distribution means comprises a tube 21 which is located within the bore of the hollow drive shaft 2 and which in use does not rotate with the cutter head and a distributor 22 located on the end of the drive shaft 2 and secured to the hub assembly 6 by bolts 23. The distributor 22 provides a chamber 24 and passages 25 which interconnect the bore of the tube 21 to distribution pipes 26 which feed fluid to the chambers ll and to the air flow inducing nozzles 17.

In addition a conical cover plate 29 is secured by brackets 31 (only one of which is shown) to the cylin drical component 8 to protect the fluid distribution and ventilator means from being damaged by broken mineral. Also air flow guide means in the form of an annu lar plate 32 and an extractor duct 33 are provided on the body of the machine 3 for extracting air away from the rotary cutter head. An extraction fan (not shown) is secured to the extraction duct 33.

in operation, as the machine 3 traverses along the working face with the rotary cutter head 1 winning coal from the working face, fluid is fed through the bore of the tube 21 to the distributor 22 located on the end of the shaft 2. The fluid is then fed via the chamber 24 and passages 25 along the radial distribution pipes 26 to the chambers [1 on the cylindrical component and to the nozzles 17. in the embodiment shown the fluid is fed continuously to all the radial pipes. Alternatively, the distribution means may be provided with a component which is mounted on the end of the tube 21 within the chamber 24 and which selectively feeds fluid to only those distribution pipes 26 currently within a preselected sector e.g. to only those distribution pipes 26 within the cutting Zone of the rotating cutter head. Thus as the head rotates fluid is fed sequentially to those chambers associated with the cutting zone of the head and when a chamber leaves the cutting zone its supply of fluid is cut off by the distribution means until it re-enters the cutting zone.

Fluid is fed from the chambers 11 along the pipes 13 to the dust suppression noz7les adjacent to the cutter tools 10 associated with the cutting zone. The water is directed from these nozzles towards the cutting tools to suppress the dust produced by the breaking mineral.

The flow of fluid along each ofthe guides 15 from the associated nozzle 17 induces an air flow along the guide in a direction away from the working face and the cutter tools 4 and towards the baffle 18. As the induced air/fluid flow impacts on the baffle 18 the dust particles which were not suppressed by fluid from the nozzle 14 adjacent the cutting zone and which were extracted with the air flow from the cutting zone tend to be arrested and fall with the fluid impacting on the bafflc 18 towards the mine floor. The air flow passes through the baffle 18 and is drawn through the extraction duct 33 to be discharged into the main ventilation air stream at a point remote from the cutting zone ensuring no recir culation if possible. Arrows X indicate the induced air flow in the zone adjacent to the working face. the flow passing through a gap 34 provided between the radially inner surface of the cylindrical component 8 and the radially outer edge of the cover plate 29.

It will be seen from the above description that the first embodiment of the present invention provides a rotary cutter head which continuously enables a high dust suppression efficiently to be achieved and which enables the zone around the head to be continuously ventilated. Any methane discharged from the broken coal is extracted from adjacent the cutter head and discharged into the main ventilation air stream. Thus, dangerously high concentrations of methane tend to be prevented from forming in the vicinity of the cutting zone.

FIG. 4 shows a second embodiment of rotary cutter head 1 in which the air flow inducing nozzles l7 (only one of which is shown) of the ventilator means are arranged to direct fluid along the air flow guides 15 in a direction towards the working face. With such an embodiment the induced air flow through the guides 15 is flowing towards the cutting zone and so it is not laden with dust particles. Thus no rem) val of dust particles is required at this stage and so no baffle i8 is provided.

The air flow discharging from the air flow guides 15 is directed towards the cutting zone via the annular gap 34 between the cylindrical component 8 and conical cover plate 29. The air flow enters the zone adjacent to the working face. scrubbing the working face and tending to remove substantially all the methane discharged from the broken coal and from the freshly formed working face. Thus, the second embodiment of rotary cutter head provides very efficient means for ventilating the zone adjacent to the cutter head. Dust suppression is achieved by the nozzles 14 arranged adjacent to the cutter tools 4 and also by the fluid discharged from the nozzles 17 which flows with the induced air flow through the annular gap 34 towards the cutting zone.

FIGS. 5 and 6 show the third embodiment of rotary cutter head which is similar to the first embodiment of cutter head described with reference to FIGS. I, 2 and 3 but which has additional ventilator means mounted on the helical loading vanes 5 so as to induce an air flow through the cylindrical component towards the hub assembly. The additional ventilator means comprises a plurality of radial hollow members 40. each of which extends through the cylindrical component 8 to provide a passage extending from a window 4I formed in the wall of the member to the zone adjacent to one of the air flow guides 15. An air flow inducing nozzle 42 is provided within each of the members 40 and arranged to direct fluid towards the adjacent air flow guide IS. The radially outer end of each of the members 40 is closed and fluid is fed to the nozzles 42 from the chambers 11 via passages 13 extending radially along the loading vanes S.

In use when fluid is fed to the nozzles 17 and 42, dust laden air is induced along the members 40 towards the air flow guides I5 where together with the induced air through the gap 34 it is induced along the air flow guide [5 towards the baffle 18.

Thus. as with the first described embodiment an air flow is induced away from the cutting zone of the cutter head, the flow tending to ventilate the zone around the head and preventing methane from forming danger ously high concentrations within this zone.

FIG. 7 shows a fourth embodiment of rotary cutter head constructed in accordance with the present invention. in which ventilator means are provided on radial surfaces adjacent the helical loading vanes 5. The ventilator means comprise a plurality of hollow members which are somewhat similar to the members 40 of the third embodiment previously described with reference to FIGS. 5 and 6 but which instead of extending through the cylindrical component 8 are arranged to guide an induced air flow adjacent the outer surface of the cylindrical component towards the machine side of the cutter head. In the embodiment shown in FIG. 7 the members 50 are L shaped but in modified constructions the members may be curved or inclined with re spect to the radial direction of the cutter head.

The members 50 may extend to the machine side of the cutter head or alternatively may extend adjacent to only a portion of the loading vanes.

In further modification of this embodiment the ventilation means may comprise only one member 50. Alternatively one member 50 may be provided on each loading vane. As a further alternative more than one mem ber 50 may be provided on each of the loading vanes.

FIGS. 8, 9 and It) show a fifth embodiment of rotary cutter head in which the air flow inducing nozzles I7 of the ventilator means are arranged to direct fluid along the air flow guides 15 in a direction away from the working face and towards the body of the mining machine (not shown}. The dust laden air is induced through passages (see FIGS. 8 and I0] which are formed in a circular cover plate 61 and each of which has an elongated crosssectional area extending radially towards the periphery of the cover plate 61, along the air flow guides 15 towards an extraction duct 62 which is mounted on the machine body (not shown) and which has an annular plate 64 extending along and ad jacent to the inner periphery of the cylindrical component 8 in order to provide an effective seal against air leakage. Thus, substantially all the induced air flow is extracted along the extraction duct 62.

The working face side of each of the passages 60 is provided with a shield arranged over the passage to defme an access to the passage which faces in a direction transverse to the axis of rotation of the rotary cutter head and in the direction opposed to the direction of rotation of the rotary cutter head. Such an arrangement of the passage access tends to prevent cut mineral from entering the passages but permit free entry of the induced dust laden air flow.

The air flow inducing nozzles 17 are fed With fluid from ducts 65 formed adjacent to the loading vanes 5 (omitted from FIG. 9). The nozzles are removable from the cylindrical component 8 to enable them to be easily cleaned or unblocked during use.

As can be seen in FIG. 9 the ventilating means comprise three air flow guides 15 equally spaced around the inner periphery of the cylindrical component 8. In FIG. 9 the cover plate 6] has been removed to expose the hub 6. The zone between the hub 6 and the cover plate 61 is divided into three equal compartments 66 by radial fins 67 secured to the hub 6 and to the inner periphery of the cylindrical component 8, and an annular plate 68 secured to the hub 6. The fins 67 sealably engage resilient pads 69 {see FIG. 8) secured to the cover plate 6] and a sealing ring 7" abuts the end of the annular ring 68. Thus. in use when the cover plate 6! is as sembled on the rotary cutter head. the three comp-art ments are separate from one another and if any one of the air flow guides should become inoperative (for example due to a blocked nozzle 17) there is little or no possibility of the induced air flow being recirculated between the operative and the non-operative air flow guides.

FIG. 11 shows a sixth embodiment of rotary cutter head in which the air flow inducing nozzles 17 (only one of which is shown) of the ventilator means are arranged to direct fluid along the air flow guide 15 in a direction towards the working face to ventilate the cutting zone of the cutter head. The induced air flow passes through the annular space 34 towards the outer periphery of the cutter head.

It will be seen from the above description that the present invention provides simple. reliable means for ventilating the zone adjacent to a rotary cutter head and for suppressing dust generated during cutting.

We claim:

1. A rotary cutter head for a mineral mining machine having a drive shaft extending towards the working mineral face. comprising a hub assembly drivably mountable on the said drive shaft of the machine, a cy lindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head, and ventilating means re mote from the axis of rotation of the cutter head and including air flow guide means and air flow inducing nozzle means for directing fluid along the said air flow guide means.

2. A rotary cutter head as claimed in claim I, in which the ventilator means is arranged to induce an air flow through the cylindrical component.

3. A rotary cutter head as claimed in claim 1, comprising a distributor for feeding fluid fed along the machines drive shaft to the air flow inducing nozzle means.

4. A rotary cutter head as claimed in claim 3, in which the cylindrical component provides a plurality of angularly spaced chambers, fluid being fed from the distributor to each chamber.

5. A rotary cutter head as claimed in claim 4, comprising dust suppression nozzle means, the fluid being fed from one of the said chambers to the air flow inducing nozzle means and to the dust suppression nozzle means.

6. A rotary cutter head as claimed in claim 1, in which the air flow guide means extends through the hub assembly to define a passage which extends between the machine side and the working face side of the hub assembly.

7. A rotary cutter head as claimed in claim 6, in which the air flow inducing nozzle means is arranged for directing fluid along the passage defined by the air flow guide means so that an air flow is induced away from the machine side of the hub assembly towards the working face side of the hub assembly.

8. A rotary cutter head as claimed in claim 6, in which the air flow inducing nozzle means is arranged for directing fluid along the passage defined by the air flow guide means so that an air flow is induced away from the working face side of the hub assembly.

9. A rotary cutter head as claimed in claim 8, in which a baffle is provided on the machine side of the air flow guide means.

10. A rotary cutter head for a mineral mining machine having a drive shaft extending towards the working mineral face, comprising a hub assembly drivably mountable on the said drive shaft of the machine, a cylindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head, ventilating means remote from the axis of rotation of the cutter head and including air flow guide means and air flow inducing nozzle means for directing fluid along the said air flow guide means, and an air flow guide plate assembly provided on the working face side of the hub assembly.

11. A rotary cutter head as claimed in claim 10, in which the air flow guide plate assembly comprises a circular plate defining an annular passage adjacent to the inner periphery of the cylindrical component 12. A rotary cutter head as claimed in claim 10, in which the air flow guide plate assembly includes a circular plate which defines a plurality of angularly spaced passages.

13. A rotary cutter head claimed in claim 12, in which the air flow guide plate assembly includes shield means arranged over the working face end of each of the said angularly spaced passages, the shield means defining an access to the passage which faces in a direction opposed to the direction of rotation of the rotary cutter head.

14. A rotary cutter head for a mineral mining machine having a drive shaft extending towards the working mineral face, comprising a hub assembly drivably mountable on the said drive shaft of the machine, a cylindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head, and ventilating means including a plurality of air flow guides angularly spaced around the cutter head, each of the air flow guides having an air flow inducing nozzle, the zone between the hub assembly and a circular plate being divided into a plurality of compartments, each compartment being associated with one of the air flow guides.

15. A mineral mining machine having a drive shaft extending towards the working face, and a rotary cutter head comprising a hub assembly drivably mounted on the said drive shaft, a cylindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head, and ventilating means remote from the axis of rotation of the cutter head and including air flow guide means and air flow inducing nozzle means for directing fluid along the said air flow guide means. 

1. A rotary cutter head for a mineral mining machine having a drive shaft extending towards the working mineral face, comprising a hub assembly drivably mountable on the said drive shaft of the machine, a cylindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head, and ventilating means remote from the axis of rotation of the cutter head and including air flow guide means and air flow inducing nozzle means for directing fluid along the said air flow guide means.
 2. A rotary cutter head as claimed in claim 1, in which the ventilator means is arranged to induce an air flow through the cylindrical component.
 3. A rotary cutter head as claimed in claim 1, comprising a distributor for feeding fluid fed along the machine''s drive shaft to the air flow inducing nozzle means.
 4. A rotary cutter head as claimed in claim 3, in which the cylindrical component provides a plurality of angularly spaced chambers, fluid being fed from the distributor to each chamber.
 5. A rotary cutter head as claimed in claim 4, comprising dust suppression nozzle means, the fluid being fed from one of the said chambers to the air flow inducing nozzle means and to the dust suppression nozzle means.
 6. A rotary cutter head as claimed in claim 1, in which the air flow guide means extends through the hub assembly to define a passage which extends between the machine side and the working face side of the hub assembly.
 7. A rotary cutter head as claimed in claim 6, in which the air flow inducing nozzle means is arranged for directing fluid along the passage defined by the air flow guide means so that an air flow is induced away from the machine side of the hub assembly towards the working face side of the hub assembly.
 8. A rotary cutter head as claimed in claim 6, in which the air flow inducing nozzle means is arranged for directing fluid along the passage defined by the air flow guide means so that an air flow is induced away from the working face side of the hub assembly.
 9. A rotary cutter head as claimed in claim 8, in which a baffle is provided on the machine side of the air flow guide means.
 10. A rotary cutter head for a mineral mining machine having a drive shaft extending towards the working mineral face, comprising a hub assembly drivably mountable on the said drive shaft of the machine, a cylindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head, ventilating means remote from the axis of rotation of the cutter head and including air flow guide means and air flow inducing nozzle means for directing fluid along the said air flow guide means, and an air flow guide plate assembly provided on the working face side of the hub assembly.
 11. A rotary cutter head as claimed in claim 10, in which the air flow guide plate assembly comprises a circular plate defining an annular passage adjacent to the inner periphery of the cylindrical component.
 12. A rotary cutter head as claimed in claim 10, in which the air flow guide plate assembly includes a circular plate which defines a plurality of angularly spaced passages.
 13. A rotary cutter head as claimed in claim 12, in which the air flow gUide plate assembly includes shield means arranged over the working face end of each of the said angularly spaced passages, the shield means defining an access to the passage which faces in a direction opposed to the direction of rotation of the rotary cutter head.
 14. A rotary cutter head for a mineral mining machine having a drive shaft extending towards the working mineral face, comprising a hub assembly drivably mountable on the said drive shaft of the machine, a cylindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head, and ventilating means including a plurality of air flow guides angularly spaced around the cutter head, each of the air flow guides having an air flow inducing nozzle, the zone between the hub assembly and a circular plate being divided into a plurality of compartments, each compartment being associated with one of the air flow guides.
 15. A mineral mining machine having a drive shaft extending towards the working face, and a rotary cutter head comprising a hub assembly drivably mounted on the said drive shaft, a cylindrical component secured around the hub assembly, a plurality of cutter tool holders provided around the periphery of the cutter head, and ventilating means remote from the axis of rotation of the cutter head and including air flow guide means and air flow inducing nozzle means for directing fluid along the said air flow guide means. 